The subject matter disclosed herein relates generally to semiconductor fabrication, and more particularly, to methods of forming a back end of line (BEOL) programmable eFUSE memory element structure, and a related semiconductor structure.
An eFUSE is a type of one-time programmable memory element incorporated into integrated circuits to enable dynamic programming of the associated circuits, even after the fabrication of the associated semiconductor device is completed. The eFUSE is programmed by blowing the fuse, which changes the state of the corresponding bit from the initial state value of “1” to a value of “0” after the fuse blow. Since an eFUSE is a one-time programmable memory type, meaning once the fuse has been blown, the process in not reversible, once a fuse has been programmed, the associated data are permanently stored.
In semiconductor processing, eFUSE structures may be formed as part of front-end-of-line (FEOL) processing, as part of the device fabrication process, or also as part of back-end-of-line (BEOL) processing where wiring is formed to connect to the semiconductor devices created during FEOL processing. Depending on where in the semiconductor build the eFUSE element is fabricated, different eFUSE designs and materials are required. Traditional FEOL fuses are silicide-based and rely on electromigration of silicide to program the fuse. The introduction of high-k metal gate materials into the FEOL integration in the state of the art advanced semiconductor technologies created challenges with blowing FEOL fuses. This has led to an increased use of BEOL eFUSE elements in advanced technology nodes.
In the BEOL, eFUSE structures may include via fuses or line fuses. Conventionally, via fuses are utilized because higher programming currents (i.e., more energy) are required in order to blow line fuses due to the larger cross-sectional area associated with line fuses.